GB1591291A

GB1591291A - Apparatus for conductor identification

Info

Publication number: GB1591291A
Application number: GB14589/77A
Authority: GB
Original assignee: GRESHAM LION DEVELOPMENTS Ltd
Current assignee: GRESHAM LION DEVELOPMENTS Ltd
Priority date: 1978-04-06
Filing date: 1978-04-06
Publication date: 1981-06-17

Description

(54) IMPROVEMENTS IN AND RELATING TO APPARATUS FOR CONDUCTOR IDENTIFICATION (71) We, GRESHAM LION DEVELOP MENTS LIMITED, a British Company, of Gresham House, Twickenham Road, Feltham, Middlesex TW13 6HA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to apparatus for identifying a given conductor in a cable or loom having multiple electrical conductors and it particularly, but not exclusively, relates to an aid to wiring systems which consist of one or more cable harnesses originating from connectors.

According to the present invention, apparatus for identifying a given conductor in a cable or loom having multiple electrical conductors of given impedance, comprises an energiser with outputs for connection each to a conductor and means for energising any selected output with an A.C. or chopped D.C. signal in response to an input signal whilst holding all the other outputs to a substantially steady level and a probe operatively connected to a detector which will produce an output signal when the probe is in the proximity of a conductor energised from the selected energiser output, the impedance of the energiser outputs at all times being such that, for the given conductor impedance, the signal level in the conductor connected to the selected energiser output is detectably different from the level of any signal that may be induced in conductors connected to the other energiser outputs.

An exemplary apparatus for this invention uses the output properties of CMOS (complementary metal oxide semiconductor devices) type integrated circuits, or any other electrical device exhibiting a similar property, of having a relatively low output impedance (of the order of 300 ohms in the case of a CMOS) both when driven high and when driven low.

The impedance of a conductor in a cable or loom is of a similar order to the output impedance of such a device so that if one conductor in a loom consisting of several conductors is energised with an alternating signal of the order of 100KHz while the other conductors in the loom are being held to a steady level (high or low), then significantly more alternating signal will be present on the energised conductor than that induced in any of the unenergised conductors. It is possible by capacitive coupling, such as by holding a probe in the individual proximity of the energised conductor, to pick up this signal, to amplify it, beat it with a signal of similar frequency to produce an audio tone and use the presence or absence of this tone to identify the conductor.

The energiser may then be used to energise the next conductor required and, in an embodiment of the invention, a display device may be used to indicate details relating to that conductor.

The invention is illustrated, by way of example, on the accompanying drawings, in which: Fig. 1 is a block diagram of an identifying apparatus in accordance with the invention; Fig. 2 is a circuit diagram of the energiser of Fig. 1; Fig. 3 is a circuit diagram of the detector of Fig. 1; Fig. 4 is a schematic of a wiring identification and testing apparatus in accordance with the invention; and Fig. 5 is a block diagram of the apparatus of Fig. 4.

As shown by Fig. 1, the apparatus for identifying a conductor or wire 100 in a cable or loom 101 having multiple electrical conductors comprises an input device 102 that accepts a programme stored on a suitable medium, for example punched paper, magnetic tape or floppy disc. The programme consists of a conventional wiring schedule that lists details of each wire to be dealt with, together with an identification code which enables the apparatus to energise the wire concerned with an identifying signal.

The identification code could either be a separate numeric identification for each wire or could be determined by the position of the data in the programme, for example details for the first wire to be identified appearing first in the programme.

The input device 102 is connected to a logic control circuit 103 which is connected both to a display device 104 and an energiser 105.

The logic control circuit 103 accepts the data from the input device 102 feeds specific machine information; such as would normally be supplied by a wiring schedule or drawings (for example wire type and size, colour, identification number, routing instructions etc.), to be displayed to the display device 104 and generates an input signal to the energiser 105. This input signal is coded, for example binary or BCD.

The energiser 105 accepts the coded input signal from the logic control circuit 103 and, in accordance with the code, feeds a low radio frequency, of the order of 100KHz, chopped D.C. or A.C. signal to one of its Outputs, whilst clamping all its other outputs to either supply rail with low impedance, the power supply also having a low impedance. Each output of the energiser 105 is connected to one of the wires in the cable loom 101 and thus the low R.F. signal can energise a selected one of the wires in the cable loom 101.

In a much simplified apparatus, the input device, control circuit and display device may be replaced by simple switches or thumb wheel switches which select the wire to be energised.

A probe 106, consisting of a short length of conductor, possibly insulated as direct electrical contact is not required by the apparatus for wire identification, is connected by a screened cable 107 to a detector 108.

The detector may consist of one or more stages of AC coupled amplifiers 109 connected to receive and amplify the signal picked up by the probe 106 and pass the amplified signal to a mixer 110. A beat frequency oscillator 111, being a local oscillator operating at a frequency close to that of the low R.F. wire identification signal, is also connected to the mixer 110 so that a beat frequency in the audio range can be produced at the output of the mixer. This audio frequency signal is fed to a buffer amplifier 112 and thence to an audio transducer or loudspeaker 113.

In an alterantive (un-illustrated) form of detector, the signal picked up by the probe is used to activate a switch to connect an audio tone generator to the audio transducer or loudspeaker.

One application for the apparatus of this invention is in a wiring identification and testing apparatus for systems which consist of one or more cable harnesses originating from connectors, in an example a cable harness or loom 101 has one end of each wire 100 connected to a connector 114 by an operator, leaving sufficient length of wire in the loom. If the cable loom forms an integral part of the equipment 115 to be wired, this operation may be performed remote from the equipment, possibly employing less skilled labour than would otherwise be possible.

The connector 114 with its wires 100 may then be assembled into the equipment 115 or may be positioned with any other assemblies which may form part of the finished loom.

The outputs of the energiser 105 are then connected one to each wire 100 in the loom 101 by a mating cable 116 having a connector 117 to mate with connector 114. The first wire to be routed and terminated is then energised and its details displayed on device 104. After the operator has dealt with this wire he presses a button on the probe 106 (not shown) which signals the apparatus to sequence on and energise and display the next wire in the wiring schedule.

An alternative, unillustrated, form of probe includes the operator as a link in the capacitive coupling, for example by means of a capacitive plate placed near the operator and connected to the input of the detector, whereby an audio tone would be emitted when the operator handled the energised wire.

An additional feature might be to provide a second, less sensitive, input to the detector to which the metallic part of a tool, such as a wire stripper or cutter, could be connected.

This would provide a further positive identification of the wire when the operator strips or cuts the wire. This further identification could be used as a signal to sequence the apparatus on to the next wire. The probe and tool could be combined.

Fig. 2 is a circuit diagram of an energiser which is shown to consist of two 4-bit latch/4-to-16 line decoder IC's, 200 and 201 respectively, which, for example, are each a type MC 14514 CMOS. These two decoders are connected in a system capable of selecting one from 32 wires.

An eight bit address code is used with a pair of decoder selectors 202 and 203 being connected to respond to the four most significant bits 27, 26, 25 and 24 of the address code to select which of the decoders 200 and 201 respectively is to be enabled. The eight bit address code would allow one wire to be selected from 256, this requiring 16 decoders.

When selected, the decoder selector 202 or 203 allows a 100 KHz chopped DC signal 204 to pass onto the inhibit pin 23 of the respective decoder via a gate 205 or 206 respectively. When not selected, the selector decoder and gate apply a high voltage (1) on to the inhibit pin of the respective de coder to cause all the outputs of that decoder to be low (0). The selected decoder reproduces the 100 KHz chopped signal at a selected one of its output pins in accordance with a code signal present at its four input pins 22, 21, 3 and 2. This code being the four least significant bits 23, 22, 21 and 20 of the address code. All the remaining outputs of the decoder are held in a quiescent low (0) output state. The latch facility of the decoders is not used.

A decoder type MC 14515 or similar device could be used in place of the type MC 14514, in which case the quiescent state of the outputs would be high (1).

An over-voltage protection circuit con sisting of two diodes D and a resistor R is shown to be connected to output 0 of I.C.

200 and similar protection circuits are indi cated as being connected to all the other outputs of I.C. 200 and I.C. 201. These circuits are to protect against connection of the decoder outputs to otherwise damaging voltages and do not affect the operation of the apparatus.

In an unshown modification to the ener giser of Fig. 2, a current sensor is connected to the supply to each decoder, IC 200 or 201, and each output is systematically caused to be energised high (1), whilst monitoring the current sensor. By this means it is possible to identify any output which has a short circuit to any other wire or the jobs earth, if this is connected to one of the outputs.

When the energised wire is shorting to another wire or earth an increase in the current supplied to the relevant decoder will be obser ved.

Fig. 3 is a circuit diagram of the detector showing it to have a coaxial input 301 con nected in series to two A.C. coupled ampli fiers 302 and 303, each being one gate of a CMOS type MC 14011 QUAD 2-INPUT "NAND" GATE IC, the two gates being biased to act as amplifiers. The output pin 4 of the second amplifier IC 302 is connected to one input pin 8 of the third gate 303 of the type MC 14011. The output BFO 111 is connect d to the other input pin 9 of gate 303, which acts as a mixer. The output from the mixer gate 303, pin 10, is connected to the input pins 12 and 13 of the fourth gate of the type MC 14011, this gate also being biased to act as a buffer amplifier 304 the output of which is connected to the base of a N-P-N transistor 305. The transducer or loudspeaker 113 is connected to the collector of transistor 305, which forms another buffer amplifier.

The beat frequency oscillator 111 is a type CD 4047 MONOSTABLE/ASTABLE MULTIVIBRATOR I.C., connected as a free-running astable multivibrator the fre quency of which is set by the values of the resistor r and capacitor c respectively connected between the R-timing pin 2 and the RC common pin 3 and the C-timing pin 1 and the common pin 3. The output pulses at pin 13 are fed to the mixer gate 303.

A squelch system might be incorporated after mixer gate 303 which would cut out the output of the transducer 113 until it reached a certain level, i.e. until the probe 106 was in close proximity to the energised wire.

Fig. 4 is a schematic of a wiring and testing apparatus wherein the display device 104 is a television monitor on which the display takes the form of 16 lines, each of 32 characters.

An overall control unit 401 houses a number of modules iincluding a cassette reader 102, forming the input device, the control logic circuitry 103, five energisers 105, each connected to the mating cable 116 and hence to the equipment 115 being wired, and the detector 108 to which the probe 106 is connected.

An instruction cassette containing the wiring instructions is loaded into the cassette reader 102. The control logic module 103 contains all the circuitry necessary to control the T.V. data display 104, operation of the cassette reader 102 and energiser sequencing.

The energiser modules 105 are each fitted with 37 way "D" type connectors each connected to the mating cable 106. The detector module 108 contains the probe circuitry and an energiser control circuit.

A TEST button 402 located on the probe 106 is connected to the detector module by an additional wire fed down the screened cable 107. Operation of the test button initiates tests for continuity and short circuits, when the probe 106 is in direct electrical contact with an identified wire under test, and, if the tests are successful test button operation causes the apparatus to step to the next instruction. Failure of a test causes the display 104 to -show the numbers of the wires in error.

Instruction cassettes are prepared using a keyboard and cassette record unit 403 that plugs into the control logic module 103. Instructional data is entered in a given code using the keyboard and is displayed on the T.V. data display 104. Once a particulay wiring instruction has been entered and checked, it is then recorded on a tape cassette.

Fig. 5 is a more detailed block diagram of the apparatus of Fig. 4. As shown, a playback cassette mechanism 501 is connected via a playback encoder 502 and a cassette interface unit 503 to a data bus 504. A processor 505 with a clock 506 at its input is also connected to the data bus 504 as are a ready only memory 507 and a read/write memory 508. Memory 507 is a programme storage memory for fixed data and memory 508 a workspace memory. The T.V. data display 104 is connected to the data bus via a T.V. memory and interface unit 509 as is a keyboard 510 via a keyboard interface unit 511. The keyboard 510 forms part of the keyboard and cassette unit 403 of which the record cassette mechanism 512 is connected to the cassette interface 503 via a record encoder 513.

A combined energiser control circuit and probe sense circuit 514 is connected to the data bus and is linked to all the energisers 105 and to the probe 106 respectively.

WHAT WE CLAIM IS: 1. Apparatus for identifying a given conductor in a cable or loom having multiple electrical conductors of a given impedance, comprising an energiser with outputs for connection each to a conductor and means for energising any selected output with an A.C.

or chopped D.C. signal in response to an input signal whilst holding all the other outputs to a substantially steady level and a probe operatively connected to a detector which will produce an output signal when the probe is in the proximity of a conductor energised from the selected energiser output, the impedance of the energizer outputs at all times being such that for the given conductor impedance, the signal level in the conductor connected to the selected energiser output is detectably different from the level of any signals that may be induced in conductors connected to the other energiser outputs.

2. Apparatus as claimed in claim 1, comprising logic control means connected to receive data from an input device and produce a coded control signal to be input to the energiser to select a particular output, cause the signal from a low radio frequency generator connected to the energiser to be fed to the particular output and cause all the other energiser outputs to be clamped to one or the other rails of a power supply for the apparatus.

3. Apparatus gs claimed in claim 1 or claim 2, wherein the probe is a short length of conductor, either insulated or uninsulated, connected by a screened cable to a radio frequency detector.

4. Apparatus as claimed in claim 3, wherein the detector includes an amplifier connected to receive and amplify the signal picked up by the probe and pass the amplified signal to a mixer and a beat frequency oscillator is connected to the mixer to produce an audio beat frequency at the mixer output.

5. Apparatus as claimed in claim 3, wherein the detector includes a switch connected to be activated by the signal picked up by the probe and connect an audio tone generator to an audio transducer or loudspeaker.

6. Apparatus as claimed in claim 1, wherein the energiser consists of at least one line decoder, a coded signal to the input of which enables an R.F. signal applied to the inhibit input of the decoder to be present at a selected output of the decoder, all the other decoder outputs being clamped either high or low; the decoder output impedance being relatively low and the same whether selected or clamped.

7. Apparatus as claimed in claim 6, wherein the energiser consists of two 4-to-16 line decoder C.M.O.S. type integrated circuits, an eight bit address code is employed of which the four most significant bits are fed to a decoder selector for each decoder, each selector being connected to one input of a gate with an R.F. signal generator being connected to another input at each gate and the output of each gate being connected to the inhibit input of a respective line decoder; the four least significant bits of the address code being fed to the four inputs of each line decoder.

8. Apparatus as claimed in claim 7, wherein an over-voltage protection circuit is connected to each line decoder output.

9. Apparatus as claimed in any of claims 6 to 8, wherein a current sensor is connected to the supply for the or each line decoder and logic means are provided to cause each line decoder output to be systemically selected and energised high; an increase in current supplied to the or each decoder indicating a short circuit in the conductor in the cable or loom to which the selected line decoder output is connected.

10. Apparatus for identifying a given conductor in a cable or loom having multiple conductors substantially as described with reference to or as shown by Fig. 1, Fig. 2 and Fig. 3; or Fig. 4; or Fig. 5 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. storage memory for fixed data and memory 508 a workspace memory. The T.V. data display 104 is connected to the data bus via a T.V. memory and interface unit 509 as is a keyboard 510 via a keyboard interface unit 511. The keyboard 510 forms part of the keyboard and cassette unit 403 of which the record cassette mechanism 512 is connected to the cassette interface 503 via a record encoder 513. A combined energiser control circuit and probe sense circuit 514 is connected to the data bus and is linked to all the energisers 105 and to the probe 106 respectively. WHAT WE CLAIM IS:

1. Apparatus for identifying a given conductor in a cable or loom having multiple electrical conductors of a given impedance, comprising an energiser with outputs for connection each to a conductor and means for energising any selected output with an A.C.